If there were an official anthem for the European debt crisis, it would be Lady Gaga's "Bad Romance," and not just because the pop star croons a few lines in French and chants the name of a continental capital. The once slow, now increasingly fast-moving economic disaster unfolding across the Atlantic is best understood as a really, really dysfunctional relationship.

As Harvard economist Ken Rogoff puts it, "Europe is like a couple that wasn't sure they wanted to get married, so instead they decided to just open a joint checking account and see how things went." They went badly. Germany, the...